Infection with Klebsiella pneumoniae carbapenemase (KPC)-producing Klebsiella pneumoniae in cancer patients

Carbapenem-resistant Klebsiella pneumoniae bloodstream infections in haematological malignances and hematopoietic stem cell transplantation: Clinical impact of combination therapy in a 10-year Brazilian cohort

Bacterial bloodstream infections (BSI) are a common threat among patients with haematological malignancies (HM) and hematopoietic stem cell transplant recipients (HSCT). The purpose of this research was to describe clinical and microbiological aspects of BSI caused by carbapenem-resistant Klebsiella pneumoniae (CRKp) and assess risk factors associated with 30-day mortality in a 10-year cohort of haematological patients. A total of 65 CRKp-BSI episodes occurring in HM patients and HSCT recipients and CRKp-BSI between January 2010 and December 2019 were retrospectively studied. Acute leukemias were the most frequently observed underlying disease (87.7%) and 18 patients (27.7%) received HSCT. Mucosal barrier injury in the gastrointestinal tract was the primary cause of bacteremia (86.1%). Also, 14 individuals (21.6%) had an Invasive Fungal Disease (IFD) throughout the episode. Regarding treatment, in 31 patients (47.7%) empirical therapy was deemed appropriate, whereas 33 (50.8%) patients received a combination therapy. Microbiological data revealed that the majority of isolates (53-58%) had the Polymyxin B co-resistance phenotype, while amikacin resistance was less common (16 samples, or 24.7%). The mortality rates at 14 and 30 days were 32.3% and 36.9%, respectively. In a multivariate Cox regression analysis, prompt appropriate antibiotic administration within three days was associated with a better outcome (Adjusted Hazard Ratio [aHR]: 0.33; 95% Confidence Interval [CI]: 0.14-0.76; p = 0.01), whereas hypotension at presentation (aHR: 3.88; 95% CI: 1.40-10.74; p = 0.01) and concurrent IFD (aHR: 2.97; 95% CI: 1.20-7.37; p = 0.02) were independently associated with death within 30 days. Additionally, a favorable correlation between combination therapy and overall survival was found (aHR: 0.18; 95%CI: 0.06-0.56; p = 0.002). In conclusion, 30-day mortality CRKp-BSI was elevated and most of the isolates were polymyxin B resistant. Early appropriate antimicrobial treatment and the use of combination therapy were linked to a better outcome.

Ceftazidime-Avibactam Improves Outcomes in High-Risk Neutropenic Patients with Klebsiella pneumoniae Carbapenemase-Producing Enterobacterales Bacteremia

Few studies have evaluated the efficacy of ceftazidime-avibactam (CA) for Klebsiella pneumoniae carbapenemase-producing Enterobacterales bacteremia (KPC-PEB) in high-risk neutropenic patients. This is a prospective multicenter observational study in high-risk neutropenic patients with multi-drug resistant Enterobacterales bacteremia. They were compared according to the resistance mechanism and definitive treatment provided: KPC-CPE treated with CA (G1), KPC-CPE treated with other antibiotics (G2), and patients with ESBL-producing Enterobacterales bacteremia who received appropriate definitive therapy (G3). Thirty-day mortality was evaluated using a logistic regression model, and survival was analyzed with Kaplan-Meier curves. A total of 238 patients were included: 18 (G1), 52 (G2), and 168 (G3). Klebsiella spp. (60.9%) and Escherichia coli (26.4%) were the Enterobacterales most frequently isolated, and 71% of the bacteremias had a clinical source. The resistance profile between G1 and G2 was colistin 35.3% vs. 36.5%, amikacin 16.7% vs. 40.4%, and tigeclycline 11.1% vs. 19.2%. The antibiotics prescribed in combination with G2 were carbapenems, colistin, amikacin, fosfomycin, tigecycline, and fluoroquinolones. Seven-day clinical response in G1 vs. G2 vs. G3 was 94.4% vs. 42.3% vs. 82.7%, respectively (p < 0.001). Thirty-day overall mortality in G1 vs. G2 vs. G3 was 22.2% vs. 53.8% vs. 11.9%, respectively (p < 0.001), and infection-related mortality was 5.5% vs. 51.9% vs. 7.7% (p < 0.001). The independent risk factors for mortality were Pitt score > 4: OR 3.63, 95% CI, 1.18-11.14 (p = 0.025) and KPC-PEB treated with other antibiotics: OR 8.85, 95% CI, 2.58-30.33 (p = 0.001), while 7-day clinical response was a protective factor for survival: OR 0.02, 95% CI, 0.01-0.08 (p < 0.001). High-risk neutropenic patients with KPC-CPE treated with CA had an outcome similar to those treated for ESBL-producing Enterobacterales, with higher 7-day clinical response and lower overall and infection-related mortality than those treated with other antibiotics. In view of these data, CA may be considered the preferred therapeutic option for KPC-PEB in high-risk neutropenic patients.

Genotypic Determination of Extended Spectrum β-Lactamases and Carbapenemase Production in Clinical Isolates of Klebsiella pneumoniae in Southwest Nigeria

INTRODUCTION

Klebsiella pneumoniae is a major pathogen implicated in healthcare-associated infections. Extended-spectrum β-lactamase (ESBL) and carbapenemase-producing K. pneumoniae isolates are a public health concern. This study investigated the existence of some ESBL and carbapenemase genes among clinical isolates of K. pneumoniae in Southwest Nigeria and additionally determined their circulating clones.

MATERIALS AND METHODS

Various clinical samples from 420 patients from seven tertiary hospitals within Southwestern Nigeria were processed between February 2018 and July 2019. These samples were cultured on blood agar and MacConkey agar, and the isolated bacteria were identified by Microbact GNB 12E. All K. pneumoniae were confirmed by polymerase chain reaction (PCR) using the 16s rRNA gene. Antibiotic susceptibility testing (AST) was done on these isolates, and the PCR was used to evaluate the common ESBL-encoding genes and carbapenem resistance genes. Genotyping was performed using multi-locus sequencing typing (MLST).

RESULTS

The overall prevalence of K. pneumoniae in Southwestern Nigeria was 30.5%. The AST revealed high resistance rates to tetracyclines (67.2%), oxacillin (61.7%), ampicillin (60.2%), ciprofloxacin (58.6%), chloramphenicol (56.3%), and lowest resistance to meropenem (43.0%). All isolates were susceptible to polymyxin B. The most prevalent ESBL gene was the TEM gene (47.7%), followed by CTX-M (43.8%), SHV (39.8%), OXA (27.3%), CTX-M-15 (19.5%), CTX-M-2 (11.1%), and CTX-M-9 (10.9%). Among the carbapenemase genes studied, the VIM gene (43.0%) was most detected, followed by OXA-48 (28.9%), IMP (22.7%), NDM (17.2%), KPC (13.3%), CMY (11.7%), and FOX (9.4%). GIM and SPM genes were not detected. MLST identified six different sequence types (STs) in this study. The most dominant ST was ST307 (50%, 5/10), while ST258, ST11, ST147, ST15, and ST321 had (10%, 1/10) each.

CONCLUSION

High antimicrobial resistance in K. pneumoniae is a clear and present danger for managing infections in Nigeria. Additionally, the dominance of a successful international ST307 clone highlights the importance of ensuring that genomic surveillance remains a priority in the hospital environment in Nigeria.

Clinical outcomes of antimicrobial resistance in cancer patients: a systematic review of multivariable models

BACKGROUND

Infections are major causes of disease in cancer patients and pose a major obstacle to the success of cancer care. The global rise of antimicrobial resistance threatens to make these obstacles even greater and hinder continuing progress in cancer care. To prevent and handle such infections, better models of clinical outcomes building on current knowledge are needed. This internally funded systematic review (PROSPERO registration: CRD42021282769) aimed to review multivariable models of resistant infections/colonisations and corresponding mortality, what risk factors have been investigated, and with what methodological approaches.

METHODS

We employed two broad searches of antimicrobial resistance in cancer patients, using terms associated with antimicrobial resistance, in MEDLINE and Embase through Ovid, in addition to Cinahl through EBSCOhost and Web of Science Core Collection. Primary, observational studies in English from January 2015 to November 2021 on human cancer patients that explicitly modelled infection/colonisation or mortality associated with antimicrobial resistance in a multivariable model were included. We extracted data on the study populations and their malignancies, risk factors, microbial aetiology, and methods for variable selection, and assessed the risk of bias using the NHLBI Study Quality Assessment Tools.

RESULTS

Two searches yielded a total of 27,151 unique records, of which 144 studies were included after screening and reading. Of the outcomes studied, mortality was the most common (68/144, 47%). Forty-five per cent (65/144) of the studies focused on haemato-oncological patients, and 27% (39/144) studied several bacteria or fungi. Studies included a median of 200 patients and 46 events. One-hundred-and-three (72%) studies used a p-value-based variable selection. Studies included a median of seven variables in the final (and largest) model, which yielded a median of 7 events per variable. An in-depth example of vancomycin-resistant enterococci was reported.

CONCLUSIONS

We found the current research to be heterogeneous in the approaches to studying this topic. Methodological choices resulting in very diverse models made it difficult or even impossible to draw statistical inferences and summarise what risk factors were of clinical relevance. The development and adherence to more standardised protocols that build on existing literature are urgent.

Retrospective Analysis of Epidemiology, Risk Factors, and Outcomes of Health Care-Acquired Carbapenem-Resistant Klebsiella pneumoniae Bacteremia in a Chinese Tertiary Hospital, 2010-2019

INTRODUCTION

In the present study, we aimed to describe the proportion of carbapenem-resistant Klebsiella pneumoniae bloodstream infection (CRKP-BSI) in KP-BSI in one Chinese tertiary hospital over 10 years and determine the risk factors and outcomes of CRKP-BSI.

METHODS

We retrospectively analyzed clinical and microbiological data of patients with KP-BSI from January 2010 to December 2019 to identify risk factors, clinical features, and outcomes using multivariate logistic regression analysis. KP-BSI only included monomicrobial BSI and health care-acquired BSI.

RESULTS

Among the total 687 isolates of KP-BSI in this study, the rate of CRKP was 39.0% (268/687); this rate in the intensive care unit (ICU) was 65.6% and that in seven high-risk departments (including four ICUs, respiratory medicine, gastroenterology medicine, and hepatobiliary surgery) was 74.6%. The annual rate of CRKP in KP-BSI ranged from 0.0% in 2010 to 54.5% in 2019. The 28-day mortality was 36.2% in patients with CRKP-BSI and 11.7% in those with carbapenem-susceptible K. pneumoniae (CSKP) BSI. Multivariable logistic regression analysis showed that prior ICU stay (odds ratio [OR] 2.485, P < 0.001), hospital stay ≥ 30 days prior to BSI (OR 1.815, P = 0.007), prior mechanical ventilation (OR 2.020, P = 0.014), prior urinary catheter (OR 1.999, P = 0.003), prior carbapenem use (OR 3.840, P < 0.001), hepatobiliary disease (OR 2.943, P < 0.001), pancreatitis (OR 2.700, P = 0.026), and respiratory disease (OR 2.493, P = 0.009) were risk factors of CRKP-BSI. Patients with a first admission (OR 0.662, P = 0.046) had a lower percentage of CRKP-BSI.

CONCLUSION

The rapidly rising rate of CRKP-BSI in KP with high mortality requires increased attention. Exposure to carbapenems, ICU stay, invasive mechanical ventilation or urinary catheter, prolonged hospital stay, hepatobiliary disease, pancreatitis, and respiratory disease were found to be risk factors for CRKP-BSI. Strict control measures should be implemented to prevent the emergence and spread of CRKP, especially in high-risk departments.

Development of a Clinical Score to Stratify the Risk for Carbapenem-Resistant Enterobacterales Bacteremia in Patients with Cancer and Hematopoietic Stem Cell Transplantation

Identifying the risk factors for carbapenem-resistant Enterobacterales (CRE) bacteremia in cancer and hematopoietic stem cell transplantation (HSCT) patients would allow earlier initiation of an appropriate empirical antibiotic treatment. This is a prospective multicenter observational study in patients from 12 centers in Argentina, who presented with cancer or hematopoietic stem-cell transplant and developed Enterobacterales bacteremia. A multiple logistic regression model identified risk factors for CRE bacteremia, and a score was developed according to the regression coefficient. This was validated by the bootstrap resampling technique. Four hundred and forty-three patients with Enterobacterales bacteremia were included: 59 with CRE and 384 with carbapenem-susceptible Enterobacterales (CSE). The risk factors that were identified and the points assigned to each of them were: ≥10 days of hospitalization until bacteremia: OR 4.03, 95% CI 1.88-8.66 (2 points); previous antibiotics > 7 days: OR 4.65, 95% CI 2.29-9.46 (2 points); current colonization with KPC-carbapenemase-producing Enterobacterales: 33.08, 95% CI 11.74-93.25 (5 points). With a cut-off of 7 points, a sensitivity of 35.59%, specificity of 98.43%, PPV of 77.7%, and NPV of 90.9% were obtained. The overall performance of the score was satisfactory (AUROC of 0.85, 95% CI 0.80-0.91). Finally, the post-test probability of CRE occurrence in patients with none of the risk factors was 1.9%, which would virtually rule out the presence of CRE bacteremia.

Klebsiella pneumoniae Carbapenemase Variants Resistant to Ceftazidime-Avibactam: an Evolutionary Overview

First variants of the Klebsiella pneumoniae carbapenemase (KPC), KPC-2 and KPC-3, have encountered a worldwide success, particularly in K. pneumoniae isolates. These beta-lactamases conferred resistance to most beta-lactams including carbapenems but remained susceptible to new beta-lactam/beta-lactamase inhibitors, such as ceftazidime-avibactam. After the marketing of ceftazidime-avibactam, numerous variants of KPC resistant to this association have been described among isolates recovered from clinical samples or derived from experimental studies. In KPC variants resistant to ceftazidime-avibactam, point mutations, insertions and/or deletions have been described in various hot spots. Deciphering the impact of these mutations is crucial, not only from a therapeutic point of view, but also to follow the evolution in time and space of KPC variants resistant to ceftazidime-avibactam. In this review, we describe the mutational landscape of the KPC beta-lactamase toward ceftazidime-avibactam resistance based on a multidisciplinary approach including epidemiology, microbiology, enzymology, and thermodynamics. We show that resistance is associated with three hot spots, with a high representation of insertions and deletions compared with other class A beta-lactamases. Moreover, extension of resistance to ceftazidime-avibactam is associated with a trade-off in the resistance to other beta-lactams and a decrease in enzyme stability. Nevertheless, the high natural stability of KPC could underlay the propensity of this enzyme to acquire in vivo mutations conferring resistance to ceftazidime-avibactam (CAZavi), particularly via insertions and deletions.

Risk Factors for Mortality and Outcomes in Hematological Malignancy Patients with Carbapenem-Resistant Klebsiella pneumoniae Bloodstream Infections

Background

This study aimed to identify risk factors for mortality and outcomes in hematological malignancy (HM) patients with bloodstream infection (BSI) caused by carbapenem-resistant Klebsiella pneumoniae (CRKP).

Methods

A retrospective study was conducted at a tertiary teaching hospital in Henan Province, China, between January 2018 and December 2021. All BSIs caused by CRKP in hospitalized HM patients were identified. Data on patient demographics, disease, laboratory tests, treatment regimens, outcomes of infection, and the antimicrobial susceptibility of each isolate were collected from medical records.

Results

A total of 129 patients with CRKP BSI were included in the study, and the 28-day mortality rate was 80.6% (104/129). In Cox analysis an absolute neutrophil count < 500 at discharge (hazard ratio [HR] 6.386, 95% confidence interval [CI] 3.074–13.266, p < 0.001), intensive care unit admission (HR 1.834, 95% CI 1.065–3.157, p = 0.029), and higher Pitt bacteremia score (HR 1.185, 95% CI 1.118–1.255, p < 0.001) were independent risk factors associated with 28-day mortality. Survival curve analysis indicated that compared with ceftazidime-avibactam-based therapy, both polymyxin b (HR 8.175, 95% CI 1.099–60.804, p = 0.040) and tigecycline (HR 14.527, 95% CI 2.000–105.541, p =0.008) were associated with a higher risk of mortality.

Conclusion

In HM patients CRKP BSI resulted in high mortality. Intensive care unit admission, higher Pitt bacteremia score, and absolute neutrophil count < 500 at discharge were independently associated with higher mortality. Early initiation of new agents such as ceftazidime-avibactam may improve outcomes.

Clinical Outcomes and Microbiological Characteristics of Sequence Type 11 Klebsiella pneumoniae Infection

Background

Sequence type 11 (ST11) Klebsiella pneumoniae (Kp) is highly prevalent in China and is a typical sequence type among KPC-producing isolates. This study aimed to evaluate the clinical outcomes and microbiological features of ST11 Kp infections.

Methods

A retrospective cohort study was conducted at Peking University Third Hospital from January 2017 to March 2021. Clinical data were collected from medical records. Antimicrobial susceptibility testing and string tests were performed. Whole-genome sequencing was used to analyze the capsular serotypes, detect virulence-associated genes, and perform multilocus sequence typing. The risk of all-cause mortality in ST11 Kp-infected patients was compared to that in non-ST11 Kp-infected patients.

Results

From 139 patients infected with Kp, 49 ST11 Kp (35.3%) strains were isolated. The Charlson comorbidity index in the ST11 group was higher than that in the non-ST11 group (3.94 ± 1.59 vs. 2.41 ± 1.54, P = 0.001). A greater number of ST11 Kp-infected patients required ICU admission (46.9 vs. 16.7%, P < 0.001) and mechanical ventilation (28.6 vs. 10.0%, P = 0.005). All ST11 isolates presented a multidrug-resistant (MDR) phenotype, and twenty-nine (59.2%) hypervirulent Kp (hvKp) were identified. Twenty-four ST11 strains presented with hypermucoviscosity. The presence of capsular types K47 and K64 was frequent in the ST11 Kp strains (P < 0.001). The key virulence-associated genes rmpA, rmpA2, iucA, iroB, and peg344 were present in 26.5, 42.9, 59.2, 0, and 26.5% of the isolates, respectively, in the ST11 group. Twenty-one ST11 isolates harbored the combination of iucA+rmpA2. The 30-day mortality rate and sequential organ failure assessment (SOFA) score were significantly higher in ST11 Kp-infected patients than in non-ST11 Kp-infected patients (P < 0.01). ST11 Kp infection appeared to be an independent risk factor for mortality in ST11 Kp-infected patients.

Conclusions

A high prevalence of the ST11 clone was found in the hospital, which accounted for elevated antimicrobial resistance and exhibited great molecularly inferred virulence. Patients with ST11 Kp infection had a tendency toward increased 30-day mortality and SOFA scores. ST11 Kp infection was an independent risk factor for mortality, suggesting that enhanced surveillance and management are essential.

Analysis of Risk Factors and Mortality of Patients with Carbapenem-Resistant Klebsiella pneumoniae Infection

Background

Carbapenem-resistant Klebsiella pneumoniae (CRKP) infection is associated with high mortality and has become a major public problem threatening patients. This study aimed to explore risk factors for death in patients with Klebsiella pneumoniae (KP) and identify risk factors for CRKP infection.

Methods

The study retrospectively analyzed clinical characteristics and microbiological data from patients infected with KP from January 2019 to October 2021 to identify risk factors and mortality, using multivariate logistic regression analysis and Cox regression analysis.

Results

A total of 214 KP inpatients were enrolled in our study. The in-hospital mortality rate was significantly higher in patients infected with CRKP (13/68, 19.12%) than carbapenem-susceptible KP (CSKP) (2/146, 1.37%) and the difference was statistically significant (P= 0.03). Multivariate Cox regression analysis showed CRKP isolation (HR 12.26, 95% CI 2.43-61.68, P = 0.002), lower TP (HR 10.50, 95% CI 1.33-82.76, P = 0.03), antibiotic days of therapy >15 (HR 0.08, 95% CI 0.01-0.56, P= 0.01) and length of stay (LOS) (HR 0.03, 95% CI 0.002-0.61, P= 0.02) were independent risk factors for death from KP. Additionally, intensive care unit (ICU) stay (OR 21.69, 95% CI 4.50-118.76, P< 0.001) and previous carbapenem exposure (OR 5.26, 95% CI 1.38-21.19, P= 0.02) are independent risk factors for CRKP.

Conclusion

Our findings showed that patients infected with CRKP have a higher in-hospital mortality rate. Identifying the independent risk factors for CRKP infection may contribute to the management of CRKP and reduce the mortality of KP patients.

Infections in Hospitalized Cancer Patients

Cancer patients are at an increased risk of developing infections that are primarily treatment-driven but may also be malignancy-driven. While cancer treatments such as chemotherapy, radiotherapy, and surgery have been known to improve malignancy morbidity and mortality, they also have the potential to weaken immune defenses and induce periods of severe cytopenia. These adverse effects pave the way for opportunistic infections to complicate a hospitalized cancer patient's clinical course. Understanding the risk each patient inherently has for developing a bacterial, fungal, or viral infection is critical to choosing the correct prophylactic treatment in conjunction with their scheduled cancer therapy. This review discusses the most common types of infections found in hospitalized cancer patients as well as the current guidelines for prophylactic and antimicrobial treatment in cancer patients. In addition, it describes the interaction between antibiotics and cancer therapies for consideration when treating infection in a cancer patient.

European Society of clinical microbiology and infectious diseases (ESCMID) guidelines for the treatment of infections caused by Multidrug-resistant Gram-negative bacilli (endorsed by ESICM -European Society of intensive care Medicine)

SCOPE

These ESCMID guidelines address the targeted antibiotic treatment of 3^rd generation cephalosporin-resistant Enterobacterales (3GCephRE) and carbapenem-resistant Gram-negative bacteria, focusing on the effectiveness of individual antibiotics and on combination vs. monotherapy.

METHODS

An expert panel was convened by ESCMID. A systematic review was performed including randomized controlled trials and observational studies, examining different antibiotic treatment regimens for the targeted treatment of infections caused by the 3GCephRE, carbapenem-resistant Enterobacterales (CRE), carbapenem-resistant Pseudomonas aeruginosa (CRPA) and carbapenem-resistant Acinetobacter baumanni (CRAB). Treatments were classified as head-to-head comparisons between individual antibiotics and monotherapy vs. combination therapy regimens, including defined monotherapy and combination regimens only. The primary outcome was all-cause mortality, preferably at 30 days and secondary outcomes included clinical failure, microbiological failure, development of resistance, relapse/recurrence, adverse events and length of hospital stay. The last search of all databases was conducted in December 2019, followed by a focused search for relevant studies up until ECCMID 2021. Data were summarized narratively. The certainty of the evidence for each comparison between antibiotics and between monotherapy vs. combination therapy regimens was classified by the GRADE recommendations. The strength of the recommendations for or against treatments was classified as strong or conditional (weak).

RECOMMENDATIONS

The guideline panel reviewed the evidence per pathogen, preferably per site of infection, critically appraising the existing studies. Many of the comparisons were addressed in small observational studies at high risk of bias only. Notably, there was very little evidence on the effects of the new, recently approved, beta-lactam beta-lactamase inhibitors on infections caused by carbapenem-resistant Gram-negative bacteria. Most recommendations are based on very-low and low certainty evidence. A high value was placed on antibiotic stewardship considerations in all recommendations, searching for carbapenem-sparing options for 3GCephRE and limiting the recommendations of the new antibiotics for severe infections, as defined by the sepsis-3 criteria. Research needs are addressed.

Reduced mortality from KPC-K.pneumoniae bloodstream infection in high-risk patients with hematological malignancies colonized by KPC-K.pneumoniae

BACKGROUND

KPC-K.pneumoniae bloodstream infection (KPC-KpBSI) mortality rate in patients with hematological malignancies is reported about 60%. The initial treatment active against KPC-K.pneumoniae is crucial for survival and KPC-K.pneumoniae rectal colonization usually precedes KPC-KpBSI. We evaluated the impact on KPC-KpBSI mortality of the preemptive use of antibiotics active against KPC-K.pneumoniae, as opposed to inactive or standard empiric antibiotics, for the empiric treatment of febrile neutropenia episodes in patients with hematological malignancy identified as KPC-K.pneumoniae intestinal carriers.

METHODS

We compared the outcomes of KPC-KpBSIs occurring in high-risk hematological patients known to be colonized with KPC-K.pneumoniae, during two time periods: March2012-December2013 (Period 1, initial approach to KPC-K.pneumoniae spread) and January2017-October2018 (Period 2, full application of the preemptive strategy). The relative importance of the various prognostic factors that could influence death rates were assessed by forward stepwise logistic regression models.

RESULTS

KPC-KpBSI-related mortality in hematological patients identified as KPC-K.pneumoniae carriers dropped from 50% in Period 1 to 6% in Period 2 (p < 0.01), from 58 to 9% in acute myeloid leukemia carriers(p < 0.01). KPC-KpBSIs developed in patients identified as KPC-K.pneumoniae carriers were initially treated with active therapy in 56% and 100% of cases in Period 1 and Period 2, respectively (p < 0.01), in particular with an active antibiotic combination in 39 and 94% of cases, respectively(p < 0.01). The 61% of KPC-KpBSI observed in Period 1 developed during inactive systemic antibiotic treatment (none in Period 2, p < 0.01), fatal in the 73% of cases. Overall, KPC-KpBSI-related mortality was 88% with no initial active treatment, 11.5% with at least one initial active antibiotic (p < 0.01), 9% with initial active combination. Only the initial active treatment resulted independently associated with survival.

CONCLUSIONS

In high-risk hematological patients colonized by KPC-K.pneumoniae, the empiric treatment of febrile neutropenia active against KPC-K.pneumoniae reduced KPC-KpBSI-related mortality to 6% and prevented fatal KPC-KpBSI occurrence during inactive systemic antibiotic treatment.

Colonization Dynamics of Multidrug-Resistant Klebsiella pneumoniae Are Dictated by Microbiota-Cluster Group Behavior over Individual Antibiotic Susceptibility: A Metataxonomic Analysis

Gastrointestinal carriage of multidrug-resistant (MDR) bacteria is one of the main risk factors for developing serious, difficult-to-treat infections. Given that there is currently no all-round solution to eliminate colonization with MDR bacteria, it is particularly important to understand the dynamic process of colonization to aid the development of novel decolonization strategies. The aim of our present study was to perform metataxonomic analyses of gut microbiota dynamics during colonization with an extended-spectrum β-lactamase (ESBL)- and carbapenemase-producing Klebsiella pneumoniae (ECKP) strain in mice; additionally, to ascertain the effects of antibiotic administration (ampicillin, ceftazidime, and ciprofloxacin) on the establishment and elimination of ECKP intestinal colonization. We have found that the phyla Bacteroidetes and Firmicutes were most dominant in all of the treatment groups; however, Bacteroidetes was more common in the groups treated with antibiotics compared to the control group. Significant differences were observed among the different antibiotic-treated groups in beta but not alpha diversity, implying that the difference is the relative abundance of some bacterial community members. Bacteria from the Lachnospiraceae family (including Agathobacter, Anaerostipes, Lachnoclostridium 11308, Lachnospiraceae UCG-004, Lachnospiraceae NK3A20 group 11318, Lachnospiraceae NK4A136 group 11319, Roseburia, and Tyzzerella) showed an inverse relationship with the carriage rate of the ECKP strain, whereas members of Enterobacteriaceae and the ECKP strain have shown a correlational relationship. Our results suggest that the composition of the microbial community plays a primary role in the MDR-colonization rate, whereas the antibiotic susceptibility of individual MDR strains affects this process to a lesser extent. Distinct bacterial families have associated into microbial clusters, collecting taxonomically close species to produce survival benefits in the gut. These associations do not develop at random, as they may be attributed to the presence of specific metabolomic networks. A new concept should be introduced in designing future endeavors for MDR decolonization, supplemented by knowledge of the composition of the host bacterial community and the identification of bacterial clusters capable of suppressing or enhancing the invader species.

Biofilm Production by Carbapenem-Resistant Klebsiella pneumoniae Significantly Increases the Risk of Death in Oncological Patients

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a prominent cause of nosocomial infections associated with high rates of morbidity and mortality, particularly in oncological patients. The hypermucoviscous (HMV) phenotype and biofilm production are key factors for CRKP colonization and persistence in the host. This study aims at exploring the impact of CRKP virulence factors on morbidity and mortality in oncological patients. A total of 86 CRKP were collected between January 2015 and December 2019. Carbapenem resistance-associated genes, antibiotic susceptibility, the HMV phenotype, and biofilm production were evaluated. The median age of the patients was 71 years (range 40–96 years). Clinically infected patients were 53 (61.6%), while CRKP colonized individuals were 33 (38.4%). The most common infectious manifestations were sepsis (43.4%) and pneumonia (18.9%), while rectal surveillance swabs were the most common site of CRKP isolation (81.8%) in colonized patients. The leading mechanism of carbapenem resistance was sustained by the KPC gene (96.5%), followed by OXA-48 (2.3%) and VIM (1.2%). Phenotypic CRKP characterization indicated that 55.8% of the isolates were strong biofilm-producers equally distributed between infected (54.2%) and colonized (45.8%) patients. The HMV phenotype was found in 22.1% of the isolates, which showed a significant (P<0.0001) decrease in biofilm production as compared to non-HMV strains. The overall mortality rate calculated on the group of infected patients was 35.8%. In univariate analysis, pneumoniae significantly correlated with death (OR 5.09; CI 95% 1.08–24.02; P=0.04). The non-HMV phenotype (OR 4.67; CI 95% 1.13–19.24; P=0.03) and strong biofilm-producing strains (OR 5.04; CI95% 1.39–18.25; P=0.01) were also associated with increased CRKP infection-related mortality. Notably, the multivariate analysis showed that infection with strong biofilm-producing CRKP was an independent predictor of mortality (OR 6.30; CI 95% 1.392–18.248; P=0.004). CRKP infection presents a high risk of death among oncological patients, particularly when pneumoniae and sepsis are present. In infected patients, the presence of strong biofilm-producing CRKP significantly increases the risk of death. Thus, the assessment of biofilm production may provide a key element in supporting the clinical management of high-risk oncological patients with CRKP infection.

First Insights into Clinical and Resistance Features of Infections by Klebsiella pneumoniae among Oncological Patients from a Referral Center in Amazon Region, Brazil

Klebsiella pneumoniae appears as one of the most prevalent pathogens among cancer patients. The present study investigates the clinical, epidemiological and microbiological aspects related to infections caused by K. pneumoniae in cancer patients treated at an oncology referral center in the state of Pará, Amazon region, Brazil. Between July 2017 to July 2019, an epidemiological, observational, cross-sectional study, with a descriptive and analytical approach was conducted, including patients with confirmed diagnosis of cancer who acquired infection by K. pneumoniae 72 h after hospital admission. K. pneumoniae isolates included in the study were obtained from different clinical materials (blood, urine, catheter tip and bladder catheter, orotracheal secretions, oncological and surgical wounds). Antimicrobial susceptibility testing and molecular detection of the carbapenemase-encoding genes were performed. A high prevalence of MDR K. pneumoniae isolates was observed, including two colistin-resistant isolates and seven isolates harboring bla_KPC-1 gene. To conclude, our findings provide the firsts insights into the epidemiology and infection by K. pneumoniae in the state of Pará, Brazil, and may be useful on treatment guidance and establishment of strategies to control the spread of resistance strains of K. pneumoniae in the region.

Inhibitory mechanism of BAC-IB17 against β-lactamase mediated resistance in methicillin-resistant Staphylococcus aureus and application as an oncolytic agent

Cancer remains a foremost cause of deaths worldwide, despite several advances in the medical science. The conventional chemotherapeutic methods are not only harmful for normal body cells but also become inactive due to the development of resistance by cancer cells. Therefore, the demand of safe anticancer agents is increasing and enforced the bottomless research on the bacteriocins. Several studies have reported the selective anticancer property of bacteriocins. Current research is the contribution to explore the exact mechanism of action and in vitro application of bacteriocin (BAC-IB17) as an oncolytic agent. In this study, β-lactamase mediated resistance of methicillin resistant Staphylococcus aureus (MRSA) was studied and inhibitory mechanism of MRSA by BAC-IB17 was investigated. Cytotoxic studies were conducted to analyze the anticancerous potential of BAC-IB17. Results revealed that BAC-IB17 inhibited the β-lactamase and produced profound effect on the membrane integrity of MRSA confirmed by scanning electron microscope (SEM). FTIR spectroscopic analysis revealed the changes in the functional groups of bacterial cells before and after treatment with BAC-IB17. BAC-IB17 also found anticancer in nature as it kills HeLa cell lines with the IC₅₀ value of 12.5 μg mL^-1 with no cytotoxic effect on normal cells at this concentration. This specific anticancer property of BAC-IB17 will make it a promising candidate for the treatment of cancer after further clinical trials. Moreover, BAC-IB17 may control MDR bacteria responsible for the secondary complications in cancer patients.

Nosocomial infections due to multidrug-resistant bacteria in cancer patients: a six-year retrospective study of an oncology Center in Western China

BACKGROUND

Bacterial infections are the most frequent complications in patients with malignancy, and the epidemiology of nosocomial infections among cancer patients has changed over time. This study aimed to evaluate the characteristics, antibiotic resistance patterns, and prognosis of nosocomial infections due to multidrug-resistant (MDR) bacteria in cancer patients.

METHODS

This retrospective observational study analyzed cancer patients with nosocomial infections caused by MDR from August 2013 to May 2019. The extracted clinical data were recorded in a standardized form and compared based on the survival status of the patients after infection and during hospitalization. The data were analyzed using independent samples t-test, Chi-square test, and binary logistic regression. P-values < 0.05 were considered significant.

RESULTS

One thousand eight patients developed nosocomial infections during hospitalization, with MDR strains detected in 257 patients. Urinary tract infection (38.1%), respiratory tract infection (26.8%), and bloodstream infection (BSI) (12.5%) were the most common infection types. Extended-spectrum β-lactamase producing Enterobacteriaceae (ESBL-PE) (72.8%) members were the most frequently isolated MDR strains, followed by Acinetobacter baumannii (11.7%), and Stenotrophomonas maltophilia (6.2%). The results of multivariate regression analysis revealed that smoking history, intrapleural/abdominal infusion history within 30 days, the presence of an indwelling urinary catheter, length of hospitalization, and hemoglobin were independent factors for in-hospital mortality in the study population. The isolated MDR bacteria exhibited high rates of sensitivity to amikacin, meropenem, and imipenem.

CONCLUSIONS

The burden of nosocomial infections due to MDR bacteria is considerably high in oncological patients, with ESBL-PE being the most predominant causative pathogen. Our findings suggest that amikacin and carbapenems actively against more than 89.7% of MDR isolates. The precise management of MDR bacterial infections in cancer patients may improve the prognosis of these individuals.

Bloodstream Infections due to Carbapenem-Resistant Klebsiella pneumoniae: A Single-Center Retrospective Study on Risk Factors and Therapy Options

We aimed to compare efficacy of different patterns of antibiotics and explore the risk factors related to mortality in patients with bloodstream infections (BSIs) due to carbapenem-resistant Klebsiella pneumoniae (CRKP). This study retrospectively included 89 patients with BSIs due to CRKP with complete data during the year of 2018 in the First Affiliated Hospital of Zhejiang University School of Medicine. Overall, the 28-day mortality was 47.2% (42/89). Multivariate analysis of Cox regression revealed that hematological malignancy (hazard ratio [HR] 5.698; 95% confidence interval [CI], 2.405-13.504; p < 0.001) and Pitt bacteremia score (HR per unit increase, 1.303; 95% CI, 1.109-1.532; p = 0.001) were identified as independent predictors for 28-day mortality. Among 70 patients with appropriate therapy, 35 received tigecycline (TGC)-based therapy, 20 received polymyxin B (PMB)-based therapy, 9 received ceftazidime/avibactam-based therapy, and 6 patients had other kinds of antibiotics, including ciprofloxacin, amikacin, and cotrimoxazole. By adjusting variables selected by crude analysis, it showed that receiving PMB-based therapy provided a survival benefit comparing with TGC-based therapy (HR, 0.068; 95% CI, 0.018-0.260; p < 0.001). Hematological malignancy and Pitt bacteremia score were independent risk factors of death in patients with BSIs due to CRKP and PMB-based therapy improved survival rate compared with TGC-based therapy.

Diagnostic performance of the Xpert Carba-R™ assay directly from rectal swabs for active surveillance of carbapenemase-producing organisms in the largest Brazilian University Hospital

BACKGROUND

The global spread of carbapenemase-producing organisms (CPO) has been considered by international health authorities as a critical public health concern. Brazil has a high CPO prevalence according to distinct publications but many routine microbiology laboratories have only phenotypic resources to evaluate this epidemiological situation, which is time-consuming and detects only carbapenem-resistant isolates missing CPO susceptible expressing a slightly decreased susceptibility. New molecular platforms can detect CPO faster but a local evaluation is essential.

AIM

To evaluate the performance of CPO detection direct from rectal swabs with the Xpert Carba-R™ assay (Cepheid, Sunnyvale, CA) in the largest Brazilian University Hospital.

METHODS

A prospective diagnostic accuracy study of CPO was performed with the collection of rectal swabs from patients admitted into the Intensive Care Unit (ICU) and into the Emergency Department (ED) between April and July 2016. The Xpert Carba-R™ assay results were compared with carbapenem-resistant Enterobacterales (CRE) surveillance cultures plus in-house PCR carbapenemase detection (reference method). In case of discordant results between methods, additional tests were performed. The limit of detection (LoD) for the CRE culture and the Xpert Carba-R™ assay were performed with contrived isolates of known carbapenemases genes.

RESULTS

A total of 921 clinical rectal swabs were analyzed being 21% (196/921) from the ICU and 79% (725/921) from the ED. Overall, the Xpert Carba-R™ assay detected 9.9% (91/921) of CPOs being 9.5% (87/921) positive only for bla_KPC and 0.4% (4/921) positive only for bla_NDM. The reference method detected 9.1% (84/921) CPO being 77 (8.4%) bla_KPC, 5 bla_VIM (0.5%) and 2 bla_NDM (0.2%). No IMP or OXA-48 like gene was detected. Overall, twelve samples, 1.3% (10 bla_KPC, 2 bla_NDM) were Xpert Carba-R™ positive but negative by the reference method. Five isolates (0.5%) were positive for bla_VIM only by in-house PCR and confirmed to be bla_VIM-2 by DNA sequencing. The Kappa value, sensitivity, specificity, positive/negative predictive values and accuracy of the Xpert Carba-R™ assay were; 0.893 (95% confidence interval [CI], 0.842-0.944), 94% (86.7-98.0), 98.6% (97.5-99.3), 86.8% (78.1-93.0), 99.4% (98.6-99.8) and 98.2% (97.3-99.1), respectively. The LoD for bla_KPC of the Xpert Carba-R™ assay and the CRE cultures were 10¹ CFU/swab.

CONCLUSION

The Xpert Carba-R™ assay is an accurate test to detect CPO directly from the rectal swabs with significant lower turnaround time (TAT) when compared to the reference method (CRE culture plus in-house PCR). Xpert Carba-R™ may, therefore, be regarded as a good and fast epidemiological tool.

Triple Versus Double Therapy for the Treatment of Severe Infections Caused by Carbapenem-Resistant Enterobacteriaceae: A Systematic Review and Meta-Analysis

Introduction

The role of combination treatment in the management of carbapenem-resistant Enterobacteriaceae infections (CRE) is still unclear. There have been no meta-analysis comparing the efficiency of triple therapy in treating CRE infections with that of double therapy. In this perspective, we conducted a meta-analysis to clarify whether triple therapy is superior to double therapy in treating patients with CRE infections.

Methods

We performed a systematic review, using PubMed and Embase without any restrictions until October 2019. Risk ratio (RR) with 95% CI were pooled to evaluate the effect of intervention.

Results

A total of 33 studies with 1,441 subjects were identified. Pooled analysis showed that triple therapy was not associated with a reduced mortality compared with double therapy (HR 0.99 95% CI 0.85-1.14, P = 0.85).

Conclusions

This meta-analysis suggests that triple therapy is not superior to double therapy in the treatment of patients with CRE infections, although the quality of evidence is generally low based on current literatures. Future well-defined, randomized controlled trials will be required to elucidate the role of triple therapy in the treatment of CRE infections.

Characterization of Phenotypic and Genotypic Traits of Klebsiella pneumoniae from Lung Cancer Patients with Respiratory Infection

Background

Klebsiella pneumoniae has been a leading healthcare-acquired infection (HAI) agent worldwide for decades. However, the epidemiological characteristics of K. pneumoniae in lung cancer patients with respiratory infection are unclear. Here, we characterized the frequency of K. pneumoniae in lung cancer patients with respiratory infection in a cancer hospital in China and determined the antibiotic resistance profile, virulence phenotype and clonal relationships among these K. pneumoniae strains.

Methods

The clinical data of lung cancer patients with respiratory infection from September 2017 to October 2018 were retrospectively evaluated. Microbiological methods, antimicrobial susceptibility tests, pulsed-field gel electrophoresis (PFGE), polymerase chain reaction (PCR) assays, Sanger sequencing and Galleria mellonella larvae infection model were used in this study.

Results

During the study period, a total of 47 lung cancer patients with respiratory infection caused by bacteria were identified, among 27 patients were identified as positive for K. pneumoniae and the positive rate was 57.45%. Among 37 nonduplicate K. pneumoniae strains from these 27 patients, 19 isolates (51.4%) were classified as multidrug resistant (MDR) with high-level resistance to, at least one agent in three or more antibiotic categories, including polymyxin B and tigecycline. Sixteen of the 37 strains (43.2%) were hypermucoviscous isolates. Extended spectrum β-lactamases-producing K. pneumoniae strains consisted of two dominant PFGE types. Furthermore, the assessment of virulence potential using a G. mellonella larvae infection model showed that K. pneumoniae isolated from these patients exhibited a high virulence level.

Conclusion

Our data showed that K. pneumoniae is the most critical cause of lung infection in patients with lung cancer in this hospital. The various drug resistance and virulence backgrounds of K. pneumoniae may make this clinical center a breeding ground for superbugs. It is paramount to enhance surveillance of K. pneumoniae strains and take control measures.

Impact of anticancer chemotherapy on the extension of beta-lactamase spectrum: an example with KPC-type carbapenemase activity towards ceftazidime-avibactam

Through their action on DNA replication, anticancer chemotherapies could increase the basal mutation rate in bacteria and increase the risk of selecting antibiotic resistant mutants. We investigated the impact of several drugs on a beta-lactamase model using KPC-type carbapenemase-producing Enterobacteriaceae. We studied the impact of anticancer chemotherapies used in pediatric hematologic malignancies on 7 clinical isolates of Enterobacteriaceae producing KPC-type carbapenemases. We compared the mutation rates from cultures with/without chemotherapy on ceftazidime-avibactam, rifampicin and ceftazidime-avibactam combined with meropenem media. Mechanisms of ceftazidime-avibactam resistance were explored on a subset of mutants. After exposure to some cytotoxic molecules, the bacterial mutation rates leading to ceftazidime-avibactam and to rifampicin resistance increased up to 10⁴-fold while we observed no emergence of resistant mutants (frequency of <10⁻¹⁰) on a meropenem combined with ceftazidime-avibactam media. Compared to the parental strains, an increased susceptibility to meropenem was observed in the ceftazidime-avibactam resistant mutants. The bla_KPC genes of ceftazidime-avibactam mutants harbored either mutations, deletions or insertions, especially in the region encoding the Ω-loop of the KPC-type carbapenemase. Anticancer chemotherapy can increase the mutation rates of bacteria accelerating the extension of KPC-type carbapenemases towards ceftazidime-avibactam, one of the last resort antimicrobial chemotherapy.

Optimizing therapy in carbapenem-resistant Enterobacteriaceae infections

PURPOSE OF REVIEW

In the absence of randomized clinical trial data, questions remain regarding the optimal treatment of carbapenem-resistant Enterobacteriaceae (CRE) infections. CRE have historically been susceptible to polymyxins, tigecycline or aminoglycosides (mostly gentamicin), and these antibiotics have long been considered the drugs of choice for CRE infections, although varying rates of resistance to all have been reported. This review looks at data from clinical studies assessing the outcomes of CRE infections treated with different antibiotic regimens.

RECENT FINDINGS

The recently approved fixed-dose combination agent, ceftazidime-avibactam (CAZ-AVI), is active against KPC and OXA-48-producing Enterobacteriaceae. The limited clinical data available on CAZ-AVI indicate that it is associated with survival benefits relative to other commonly used regimens, although development of resistance is a concern. New drugs active against CRE isolates (including the recently approved meropenem-vaborbactam) are in different stages of development.

SUMMARY

CAZ-AVI and meropenem-vaborbactam seem destined to become the backbone of target therapy for high-risk patients with severe infections caused by susceptible CRE strains. However, empirical therapy should be based on risk factors to be defined in the near future, whereas the necessity of combinations with CAZ-AVI requires further studies. Polymyxins are still important options for low-risk patients with susceptible CRE infections, but also for high-risk patients in regions where metallo-β-lactamase-producing CRE predominate because CAZ-AVI and meropenem-vaborbactam are both ineffective against these strains.

Infections Due to Multidrug-Resistant Bacteria in Oncological Patients: Insights from a Five-Year Epidemiological and Clinical Analysis

Bacterial infections are frequent complications in cancer patients. Among them, those caused by multidrug-resistant (MDR) bacteria increase morbidity and mortality mainly because of limited therapeutic options. Current knowledge regarding MDR infections in patients with solid tumors is limited. We assessed the epidemiology and risk factors of increased mortality in these patients. In this retrospective five-year single cohort observational study, we included all oncological patients with MDR infections. Cancer-related parameters, comorbidities, prior use of antibiotics, previous surgical interventions and hospitalization, as well as the use of invasive procedures were investigated as potential risk factors causing adverse outcomes. Seventy-three patients with MDR infection were included: 37% with carbapenem-resistant Klebsiella pneumoniae, 24% with oxacillin-resistant Staphylococcus aureus (MRSA) and 21% with carbapenem-resistant Acinetobacter baumanni. Previous colonization with MDR bacteria was detected in 14% patients, while 20% of the patients presented MDR colonization or infection at ward admission. Mortality during the infection episode was 32%. Duration of hospitalization and CRP were statistically significant risk factors of mortality, whereas administration of guided antibiotics was a protective factor. Knowledge of local epidemiology of MDR bacteria can help physicians promptly identify cancer patients at risk of MDR infections and initiate timely effective empirical antibiotic treatment that can eventually improve the overall therapeutic management.

Effect of carbapenem restriction on prescribing trends for immunocompromised wards at an academic medical center

The recently described proportion of carbapenem consumption metric was used to assess the effectiveness of formulary restriction for carbapenems for 2 units housing predominantly immunocompromised patients at a large academic medical center. Interrupted time series analysis revealed a significant decrease in meropenem use for hematology-oncology and bone marrow transplant units after restriction.

An in-depth analysis of nosocomial bloodstream infections due to Gram-negative bacilli: clinical features, microbiological characteristics and predictors of mortality in a 1 year, prospective study in a large tertiary care Italian hospital

BACKGROUND

Bloodstream infections (BSI) due to Gram negative bacilli (GNB) represent a major concern among nosocomial infections, since they are noticeably associated with a high mortality rates, increase of healthcare costs and prolongation of hospital stay.

METHODS

Over a 12-month period (2014-2015) all the adult patients admitted to a university-based Italian hospital were monitored for development of BSIs due to GNB. Multiple logistics regression models were performed to assess the impact of patients' risk factors on the in-hospital and 14-day mortality.

RESULTS

During the study period 208 patients were diagnosed with at least a BSI due to a Gram negative species for an incidence rate of 12.8 cases/1,000 admissions (95%CI: 11.2-14.7). Multivariate analyses showed that multiple organ dysfunctions along with immune deficit and inadequate therapy in the first 48hrs were associated with a higher risk of death.

CONCLUSIONS

A thorough evaluation of both immune status and organ dysfunction at the onset of septic events, along with adequate antimicrobial therapy appear to be the most reliable factors in predicting the outcome in these infections. SOFA score can be efficaciously substituted to the single organ dysfunctions analysis in predicting mortality after these events.

Nephrotoxicity prevalence in patients treated with polymyxins: a systematic review with meta-analysis of observational studies

Colistin and polymyxin B are increasingly reintroduced in clinical practice due to the absence of effective antibiotics for the treatment of emerging infections caused by gram-negative bacteria. The synthesis of current evidence on the characteristics of polymyxins, especially regarding nephrotoxicity, is necessary. This study aims to conduct a systematic review and meta-analysis of cohort-type observational studies in order to identify the prevalence of nephrotoxicity in patients treated with either colistin or polymyxin B. PubMed, Scopus, and DOAJ electronic databases were searched, and manual searches were done. Cohort studies evaluating renal damage (nephrotoxicity) in adult patients caused by colistin or polymyxin B were included. Meta-analyses of the prevalence of nephrotoxicity as well as cumulative meta-analysis and meta-regression were conducted. After the systematic searches, 95 cohorts (n = 7911 patients) were included for analysis. The nephrotoxicity prevalence was 26.7% [confidence interval (CI) 95%: 22.8-30.9%] for colistin and 29.8% (CI 23.8-36.7%) for polymyxin B (P = 0.720). The publication year of the studies, the criteria used to classify renal damage, and the nephrotoxicity as primary or secondary outcome showed a significant influence on the adverse event rates.

Tailoring antimicrobials in febrile neutropenia: using faster diagnostic and communication tools to improve treatment in the era of extensively resistant pathogens

Febrile Neutropenia represents a medical emergency and the use of appropriate antimicrobial therapy is essential for a better outcome. Although being time-consuming, conventional cultures and antimicrobial susceptibility tests remain the golden standard practices for microbiology identification. Final reports are typically available within several days. Faster diagnostic tools, such as species identification trough Matrix Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF) and molecular techniques might help to shorten time to diagnostic and also guide definitive therapy in this scenario. Here we present a case in which the use of a diagnostic molecular workflow combining MALDI-TOF and real-time PCR for relevant genes codifying antibiotic resistant integrated with instant communication report, led to a tailored and more appropriate treatment in a patient presenting with febrile neutropenia.

Predator Versus Pathogen: How Does Predatory Bdellovibrio bacteriovorus Interface with the Challenges of Killing Gram-Negative Pathogens in a Host Setting?

Bdellovibrio bacteriovorus is a small deltaproteobacterial predator that has evolved to invade, reseal, kill, and digest other gram-negative bacteria in soils and water environments. It has a broad host range and kills many antibiotic-resistant, clinical pathogens in vitro, a potentially useful capability if it could be translated to a clinical setting. We review relevant mechanisms of B. bacteriovorus predation and the physiological properties that would influence its survival in a mammalian host. Bacterial pathogens increasingly display conventional antibiotic resistance by expressing and varying surface and soluble biomolecules. Predators coevolved alongside prey bacteria and so encode diverse predatory enzymes that are hard for pathogens to resist by simple mutation. Predators do not replicate outside pathogens and thus express few transport proteins and thus few surface epitopes for host immune recognition. We explain these features, relating them to the potential of predatory bacteria as cellular medicines.

Mortality due to KPC carbapenemase-producing Klebsiella pneumoniae infections: Systematic review and meta-analysis: Mortality due to KPC Klebsiella pneumoniae infections

INTRODUCTION

KPC carbapenemase-producing Klebsiella pneumoniae (KPC-KP) has become a major public health challenge. Accordingly, this study sought to use a systematic review of the scientific literature to ascertain the mortality of KPC-KP infection, and analyze such mortality by country, year of publication, hospital ward, and type of interpretation used to define carbapenem resistance.

METHODOLOGY

A search without language restrictions was made of the MEDLINE, CENTRAL, EBSCO, LILACS and EMBASE databases from 1996 through June 2017, to locate all studies which had determined the existence of KPC-KP infection. We then performed a meta-analysis of all studies that reported KPC-KP infection-related mortality, and analyzed mortality by subgroup in accordance with standard methodology.

RESULTS

A total of 51 papers were included in the systematic review. From 2005 through 2017, data on KPC-KP infection were reported in 5124 patients, with an average of 465 patients per year. The most widely studied type of infection was bacteremia (28∙0%). The meta-analysis showed that overall mortality for the 37 studies was 41.0% (95%CI 37.0-44.0), with the highest mortality rates being observed in oncology patients, 56.0% (95%CI 38.1-73.0), and Brazil, 51.3% (95%CI 43.0-60.0).

CONCLUSION

KPC-KP infection-related mortality is high, is manifested differently in some countries, and is highest among oncology patients.

Treatment of Infections Caused by Extended-Spectrum-Beta-Lactamase-, AmpC-, and Carbapenemase-Producing Enterobacteriaceae

Therapy of invasive infections due to multidrug-resistant Enterobacteriaceae (MDR-E) is challenging, and some of the few active drugs are not available in many countries. For extended-spectrum β-lactamase and AmpC producers, carbapenems are the drugs of choice, but alternatives are needed because the rate of carbapenem resistance is rising. Potential active drugs include classic and newer β-lactam-β-lactamase inhibitor combinations, cephamycins, temocillin, aminoglycosides, tigecycline, fosfomycin, and, rarely, fluoroquinolones or trimethoprim-sulfamethoxazole. These drugs might be considered in some specific situations. AmpC producers are resistant to cephamycins, but cefepime is an option. In the case of carbapenemase-producing Enterobacteriaceae (CPE), only some "second-line" drugs, such as polymyxins, tigecycline, aminoglycosides, and fosfomycin, may be active; double carbapenems can also be considered in specific situations. Combination therapy is associated with better outcomes for high-risk patients, such as those in septic shock or with pneumonia. Ceftazidime-avibactam was recently approved and is active against KPC and OXA-48 producers; the available experience is scarce but promising, although development of resistance is a concern. New drugs active against some CPE isolates are in different stages of development, including meropenem-vaborbactam, imipenem-relebactam, plazomicin, cefiderocol, eravacycline, and aztreonam-avibactam. Overall, therapy of MDR-E infection must be individualized according to the susceptibility profile, type, and severity of infection and the features of the patient.

A Systematic Review and Meta-analyses of the Clinical Epidemiology of Carbapenem-Resistant Enterobacteriaceae

Carbapenem-resistant Enterobacteriaceae (CRE) are major health care-associated pathogens and responsible for hospital outbreaks worldwide. To prevent a further increase in CRE infections and to improve infection prevention strategies, it is important to summarize the current knowledge about CRE infection prevention in hospital settings. This systematic review aimed to identify risk factors for CRE acquisition among hospitalized patients. In addition, we summarized the environmental sources/reservoirs and the most successful infection prevention strategies related to CRE. A total of 3,983 potentially relevant articles were identified and screened. Finally, we included 162 studies in the systematic review, of which 69 studies regarding risk factors for CRE acquisition were included in the random-effects meta-analysis studies. The meta-analyses regarding risk factors for CRE acquisition showed that the use of medical devices generated the highest pooled estimate (odds ratio [OR] = 5.09; 95% confidence interval [CI] = 3.38 to 7.67), followed by carbapenem use (OR = 4.71; 95% CI = 3.54 to 6.26). To control hospital outbreaks, bundled interventions, including the use of barrier/contact precautions for patients colonized or infected with CRE, are needed. In addition, it is necessary to optimize the therapeutic approach, which is an important message to infectious disease specialists, who need to be actively involved in a timely manner in the treatment of patients with known CRE infections or suspected carriers of CRE.

Triple combination antibiotic therapy for carbapenemase-producing Klebsiella pneumoniae: a systematic review

Background

The spread of carbapenemase-producing K. pneumoniae (CPKP) has become a significant problem worldwide. Combination therapy for CPKP is encouraging, but polymyxin resistance to many antibiotics is hampering effective treatment. Combination therapy with three or more antibiotics is being increasingly reported, therefore we performed a systematic review of triple combination cases in an effort to evaluate their clinical effectiveness for CPKP infections.

Methods

The PubMed database was searched to identify all published clinical outcomes of CPKP infections treated with triple combination therapy. Articles were stratified into two tiers depending on the level of clinical detail provided. A tier 1 study included: antibiotic regimen, regimen-specific outcome, patient status at onset of infection, and source of infection. Articles not reaching these criteria were considered tier 2.

Results

Thirty-three studies were eligible, 23 tier 1 and ten tier 2. Among tier 1 studies, 53 cases were included in this analysis. The most common infection was pneumonia (31%) followed by primary or catheter-related bacteremia (21%) and urinary tract infection (17%). Different combinations of antibiotic classes were utilized in triple combinations, the most common being a polymyxin (colistin or polymyxin B, 86.8%), tigecycline (73.6%), aminoglycoside (43.4%), or carbapenem (43.4%). Clinical and microbiological failure occurred in 14/39 patients (35.9%) and 22/42 patients (52.4%), respectively. Overall mortality for patients treated with triple combination therapy was 35.8% (19/53 patients).

Conclusions

Triple combination therapy is being considered as a treatment option for CPKP. Polymyxin-based therapy is the backbone antibiotic in these regimens, but its effectiveness needs establishing in prospective clinical trials.

Carbapenem-resistant Enterobacteriaceae in special populations: Solid organ transplant recipients, stem cell transplant recipients, and patients with hematologic malignancies

Carbapenem-resistant Enterobacteriaceae (CRE) are a major global public health concern and pose a serious threat to immunocompromised hosts, particularly patients with hematologic malignancies and solid organ (SOT) and stem cell transplant recipients. In endemic areas, carbapenem-resistant Klebsiella pneumoniae infections occur in 1-18% of SOT recipients, and patients with hematologic malignancies represent 16-24% of all patients with CRE bacteremia. Mortality rates approaching 60% have been reported in these patient populations. Early diagnosis and rapid initiation of targeted therapy is critical in the management of immunocompromised hosts with CRE infections, as recommended empiric regimens are not active against CRE. Therapeutic options are limited by antibiotic-associated toxicities, interactions with immunosuppressive agents, and paucity of antibiotic options currently available. Prevention of CRE infection in these patients requires a multidisciplinary approach involving hospital epidemiology and antimicrobial stewardship. Large, multicenter studies are needed to develop risk-stratification tools to assist in guiding the management of these individuals.

Carbapenem-resistant Klebsiella pneumoniae in high-risk haematological patients: factors favouring spread, risk factors and outcome of carbapenem-resistant Klebsiella pneumoniae bacteremias

BACKGROUND

Carbapenem-resistant Klebsiella pneumoniae (CRKP) spread and infections in patients with haematological malignancies are a serious concern especially in endemic areas. Treatment failures and delay in appropriate therapy for CRKP infections are frequent and the mortality rate associated with CRKP bacteremia in neutropenic haematological patients is reported about 60%.

METHODS

Haematological patients harboring CRKP hospitalized between February 2012 and May 2013 in an Italian Teaching hospital were examined. Conditions favouring CRKP spread in a haematological unit, risk factors for bacteremia in CRKP-carriers and for CRKP bacteremia-related death were evaluated in this observational retrospective study.

RESULTS

CRKP was isolated in 22 patients, 14 (64%) had bacteremia. Control measures implementation, particularly the weekly rectal screening for CRKP performed in all hospitalized patients and contact precautions for CRKP-carriers and newly admitted patients until proved CRKP-negative, reduced significantly the CRKP spread (14 new carriers identified of 131 screened patients vs 5 of 242 after the intervention, p = 0.001). Fifty-eight percent of carriers developed CRKP bacteremia, and acute myeloid leukemia (AML) resulted independently associated with the bacteremia occurrence (p = 0.02). CRKP bacteremias developed mainly during neutropenia (86%) and in CRKP-carriers (79%). CRKP bacteremias were breakthrough in 10 cases (71%). Ten of 14 patient with CRKP bacteremias died (71%) and all had AML. The 70% of fatal bacteremias occurred in patients not yet recognized as CRKP-carriers and 80% were breakthrough. Initial adequate antibiotic therapy resulted the only independent factor able to protect against death (p = 0.02).

CONCLUSIONS

The identification of CRKP-carriers is confirmed critical to prevent CRKP spread. AML patients colonized by CRKP resulted at high risk of CRKP-bacteremia and poor outcome and the adequacy of the initial antibiotic therapy may be effective to improve survival. To limit the increase of resistance, the extensive use of antibiotics active against CRKP should be avoided, but in the setting of high CRKP pressure and high-risk CRKP-colonized haematological patients, timely empiric antibiotic combinations active against CRKP could be suggested as treatment of febrile neutropenia.

The epidemiology of carbapenemases in Latin America and the Caribbean

INTRODUCTION

Enterobacteriaceae, Pseudomonas spp., and Acinetobacter spp. infections are major causes of morbidity and mortality, especially due to the emergence and spread of β-lactamases. Carbapenemases, which are β-lactamases with the capacity to hydrolyze or inactivate carbapenems, have become a serious concern as they have the largest hydrolytic spectrum and therefore limit the utility of most β-lactam antibiotics. Areas covered: Here, we present an update of the current status of carbapenemases in Latin America and the Caribbean. Expert commentary: The increased frequency of reports on carbapenemases in Latin America and the Caribbean shows that they have successfully spread and have even become endemic in some countries. Countries such as Brazil, Colombia, Argentina, and Mexico account for the majority of these reports. Early suspicion and detection along with implementation of antimicrobial stewardship programs in all healthcare settings are crucial for the control and prevention of carbapenemase-producing bacteria.

The growing threat of multidrug-resistant Gram-negative infections in patients with hematologic malignancies

Prolonged neutropenia and chemotherapy-induced mucositis render patients with hematologic malignancies highly vulnerable to Gram-negative bacteremia. Unfortunately, multidrug-resistant (MDR) Gram-negative bacteria are increasingly encountered globally, and current guidelines for empirical antibiotic coverage in these patients may not adequately treat these bacteria. This expansion of resistance, coupled with traditional culturing techniques requiring 2-4 days for bacterial identification and antimicrobial susceptibility results, have grave implications for these immunocompromised hosts. This review characterizes the epidemiology, risk factors, resistance mechanisms, recommended treatments, and outcomes of the MDR Gram-negative bacteria that commonly cause infections in patients with hematologic malignancies. We also examine the infection prevention strategies in hematology patients, such as infection control practices, antimicrobial stewardship, and targeted decolonization. Finally, we assess the strategies to improve outcomes of the infected patients, including gastrointestinal screening to guide empirical antibiotic therapy, new rapid diagnostic tools for expeditious identification of MDR pathogens, and use of two new antimicrobial agents, ceftolozane/tazobactam and ceftazidime/avibactam.

Bloodstream infection caused by extensively drug-resistant Acinetobacter baumannii in cancer patients: high mortality associated with delayed treatment rather than with the degree of neutropenia

This study aimed to describe severe infections with extensively drug-resistant Acinetobacter baumannii-calcoaceticus complex (XDR-ABC), as well as to investigate risk factors for mortality, in cancer patients. It was a retrospective study including all patients diagnosed with XDR-ABC bacteraemia during hospitalization in the intensive care unit of a cancer hospital between July 2009 and July 2013. Surveillance cultures were collected weekly during the study period, and clonality was analysed using pulsed field gel electrophoresis (PFGE). We analysed underlying diseases, oncology therapy, neutrophil counts, infection site and management of infection, in terms of their correlation with 30-day mortality. During the study period, 92 patients with XDR-ABC bacteraemia were identified, of whom 35 (38.0%) were patients with haematological malignancy. We identified XDR-ABC strains with four different profile patterns, 91.3% of patients harbouring the predominant PFGE type. Of the 92 patients with XDR-ABC bacteraemia, 66 (71.7%) had central line-associated bloodstream infections; infection occurred during neutropenia in 22 (23.9%); and 58 (63.0%) died before receiving the appropriate therapy. All patients were treated with polymyxin, which was used in combination therapy in 30 of them (32.4%). The 30-day mortality rate was 83.7%. Multivariate analysis revealed that septic shock at diagnosis of XDR-ABC infection was a risk factor for 30-day mortality; protective factors were receiving appropriate therapy and invasive device removal within the first 48 h. Among cancer patients, ineffective management of such infection increases the risk of death, more so than do features such as neutropenia and infection at the tumour site.

Risk factors for incidence and case-fatality rates of healthcare-associated infections: a 20-year follow-up of a hospital-based cohort

Information is lacking on the integrated evaluation of mortality rates in healthcare-associated infections (HAIs). Our aim was to differentiate the risk factors responsible for the incidence from those for the case-fatality rates in association with HAIs. We therefore examined the time trends of both incidence and case-fatality rates over a 20-year period at a tertiary-care teaching medical centre in Taiwan and the mortality rate was expressed as the product of the incidence rate and the case-fatality rate. During the study period the overall mortality rate fell from 0·46 to 0·32 deaths/1000 patient-days and the incidence rate fell from 3·41 to 2·31/1000 patient-days, but the case-fatality rate increased marginally from 13·5% to 14·0%. The independent risk factors associated with incidence of HAIs were age, gender, infection site, admission type, and department of hospitalization. Significant prognostic factors for HAI case-fatality were age, infection site, intensive care, and clinical department. We conclude that the decreasing trend for the HAI mortality rate was accompanied by a significant decline in the incidence rate and this was offset by a slightly increasing trend in the case-fatality rate. This deconstruction approach could provide further insights into the underlying complex causes of mortality for HAIs.

Risk factors and outcome of infections with Klebsiella pneumoniae carbapenemase-producing K. pneumoniae in kidney transplant recipients

INTRODUCTION

Solid organ transplant recipients are especially susceptible to healthcare-associated infections with Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp-HAIs). The aim of the study was to evaluate risk factors and outcome of these infections in kidney transplant recipients.

METHODS

This was a retrospective cohort of kidney transplant (KTx) recipients between January 2009 and December 2013. Cases were defined as patients who developed KPC-Kp-HAI, confirmed by PCR for bla( KPC) gene after KTx during the study period. We analysed variables related to recipient; induction immunosuppressant therapy; delayed graft function; use of invasive devices; SOFA score on the first day of infection; type of therapy; time from positive culture to appropriate antimicrobial therapy; bacteraemia; and concomitant infection. Outcome measures were the occurrence of KPC-Kp-HAI and 30-day mortality after KPC-Kp-HAI.

RESULTS

A total of 1,101 were submitted to KTx in the period, 21 patients were classified as infected with KPC-Kp. Another ten patients had KPC-Kp-HAI in the period and were transplanted before 2009. Of those 31 patients, 48.4 % showed evidence of prior colonization and 38.7 % had bacteraemia. The most common site of infection was the surgical wound. Risk factors for KPC-Kp-HAI were multi-organ transplantation and the use of a ureteral stent. Eight of the infected patients experienced recurrence of the infection. The 30-day mortality rate was 41.9 %. Survival was significantly lower among the patients with KPC-Kp-HAI (72 vs. 89.1 %; P = 0.002). The only risk factor independently associated with 30-day mortality was an elevated SOFA score on the first day of infection.

CONCLUSIONS

In KTx recipients, the occurrence of KPC-Kp-HAI was related to invasive devices and type of transplant; these infections had a high rate of recurrence and reduced survival after KTx.